Limiting farm runoff not curbing pollution

On The Bay

Agriculture: The use of commercial fertilizers and animal manure has not declined in the Chesapeake drainage, keeping nitrogen and phosphorus levels high.

November 23, 2001|By Tom Horton | Tom Horton,SUN STAFF

AFTER MORE than a decade of effort to reduce agricultural pollution, a major source of the Chesapeake Bay's ills, scientists and environmental managers are questioning how much effect it's having.

Despite impressive action by many farmers, pollution in rivers that drain farmland remains high, and the two basic causes of it don't seem to have diminished.

Sales of commercial fertilizer across the bay's 64,000-square-mile, six-state watershed have remained stable since the late 1980s, and manure from farm animals has increased in many areas.

Both are prime sources of nitrogen and phosphorus, which wash into the bay and tributaries, killing underwater grasses, depleting oxygen and setting the stage for toxic algae blooms.

Sewage and air pollution from cars and industries also are dominant sources of this "nutrient" pollution. The technology, money and legal authority exist to make controlling both relatively straightforward.

Agriculture is spread across millions of acres, managed by thousands of individuals, and deeply rooted in voluntary approaches to solving problems. Only in the past two decades were nutrients from farms identified as a bay concern.

The solution pursued by the federal-state Chesapeake Bay restoration program has been to get farmers to install "Best Management Practices" to reduce polluted runoff and losses of soil to waterways.

These can range from manure storage lagoons and planting pollution buffers of grass or forest near waterways, to shipping excess manure to farms whose crops need the nutrients.

Much emphasis has been put on getting farmers to substitute manure from their cattle, swine and chickens for commercial fertilizer.

As farms agree to such plans, they get credit for reducing nutrients flowing to the bay. These paper reductions, amounting to millions of pounds of nitrogen and phosphorus, are plugged into a computer model that is used to calculate the impact of cleanup strategies on the bay's water quality.

But now, "there is a good deal of skepticism about those numbers. ... If we have this much nutrient management, why isn't [pollution] decreasing more?" said Lewis Linker, an environmental scientist with the Environmental Protection Agency who works with the bay computer model.

"Somewhere there's a discrepancy between what our computer model of the watershed is saying and what's really happening. It's fair to say we should be skeptical about how much credit we're giving agriculture," agreed Scott Phillips, a scientist with the U.S. Geological Survey.

Phillips is one of the authors of a major USGS study that looked at nutrient trends on all major bay tributaries from 1985 to 1998.

It found no reduction in nutrients, as measured in water entering the bay, on most of the rivers. However, the weather, bay-wide, was wetter, and runoff from the land higher during the 1990s.

Adjusting for that, it appeared that compared with the 1980s, agriculture had made some significant nutrient reductions, even if higher runoff due to wet weather had offset it.

But since the report was concluded, 1999 and 2000 data have shown that pollution loads in the rivers remained high even though both years were dryer than normal, Phillips said. "So you have to question what is going on," he added.

That's the big picture. The small picture is equally perplexing. Take German Branch, a tributary of Maryland's Choptank River, that drains 20 square miles of rural and agricultural lands.

A decade after Maryland targeted German Branch for a whole suite of agricultural best-management practices, with good cooperation from farmers there, nutrient levels remain about the same.

For several years, the state thought improvements by farmers were being masked by "lag times" - it can take years for cleaner runoff to move from farm fields through ground water into streams.

But that's been ruled out now, says John L. McCoy, the German Branch project leader with the state Department of Natural Resources.

McCoy thinks that nutrients going on the land around German Branch haven't been reduced as much as everyone assumed.

Where does this leave us, given that huge nutrient reductions will be needed from all sources to meet bay restoration goals during the next decade?

"We still have more questions than answers. ... But at least now we know what we are up against, and that is a significant achievement," says Ken Staver, a University of Maryland agricultural researcher who has analyzed German Branch.

I agree with Staver that this is no time for finger pointing and blame. It is time to acknowledge that the current approach to farm pollution won't cut it - time to stop assuming that paper farm pollution control plans are all working.

An immediate step would be to plant winter "cover crops" on virtually all farm fields. This technique, developed by Staver and others, is one of the few proven ways to sop up nutrients before they run off.

Costing $25 dollar an acre, cover crops are cheaper per pound of nutrient removed than sewage treatment or air pollution control. Farmers have shown they will do it when financial assistance is available.

Across the watershed, we have to get real nutrient reductions from all farms, not just a progressive minority. And they've got to be paid for - not just by those who grow food, but by everyone who eats it.

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